This post was published long before the Mists of Pandara Expansion.
The tips and techniques explained here may be outdated.

Noodling on Holy Spec

In Instances:
+int +spelldamage +crit gear/enchantments
Devotion Aura (or spell specific aura as needed)
Holy Light/Flash of Light/Holy Shock healing
For long fights:
Seal of Light/Judgment to get Judgment of Light on mob
Seal of Wisdom (so I can get add’l mana)

Solo:
+int +spelldamage +crit gear/enchantments
AOE poisoning shield with shield spike (maybe with Darkmoon Fury Deck Trinket eventually)
Retribution Aura
Seal of the Crusader/Judgment to get Judgment of Crusader on Mob (or Seal of Light/Judgment of Light need to try it out)
Seal of Righteousness/Judgment or Seal of Vengeance(on very long fights) for busty holy damage.
Occasional Holy Shock/Consecrate
Occasional Heals to myself

Having been a Holy paladin from levels 10 all the way to 66 when I decided to go to where my heart lay with tanking, I can safely say that in general Holy Shock is not an overly useful tool. It heals too little, as an instant cast spell it gets only a small boost from even a lot of +healing, and it’s very mana inefficient. Unless you’re using it as a quick bandaid while another tosses a stronger heal on the tank, you’re probably best off using Flash of Light. The global cooldown caused by Holy Shock is about the same as the cast time of Flash of Light and heals for a lot more.

I’ll give more concrete advice when I get home and can see your planned spec.

I just hate to spend 2 points on a skill I -might- use once every 40 minutes.

I’d much rather spend it on that something that
– Benefits heals (more healing or more mana)
– Benefits the whole party
– Makes me die slower
– Kills mobs faster in solo.

Candidates for the extra points:
– Unyielding Faith is tempting as it means that 5% more of the time I’ll be available to heal.
– Blessed Life is tempting in that it means less damage when I am hit
– Improved Devotion Aura – even though I agree this is a crap talent, at 5/5 it’s adding ~1000 armor to everyone nearby in the party. For clothies or leather wearers that’s huge. More armor = less heals.
– Improved Seal of Righteousness – more damage good for solo

Now, if LOH put me at 1/2 health and 1/2 mana Iâ€™d be sorely temptedâ€¦ but losing all my mana for a little bit more armor.. and full healthâ€¦ eeh.

The full health is the good part.. and I get that without spending the two points.

Thing to remember, LoH costs all of your current mana. If you ever find yourself around 0 mana, you can hold off and drop the healing bomb on tank for almost no mana, thus giving you time to recover your mana afterwards without the immediate need for heals. In the end, LoH is an “Oh shit” button and should be used as such. Esp. when used on a paladin tank for whom it would give them health (and mana from said healing) and additional mana from the effect it’s a quite effective tool.

Have you tried using a big two-handed weapon in place of your one-hander and shield? You take considerably more physical damage, but you also dish it out considerably better. Without any of the improved blocking talents, I’m having a hard time believing that the shield is making up for the massive white DPS loss. Certainly on a dedicated prot grinder the shield is a great DPS tool, because you block all the time, but I’d at least switch to a two-hander while fighting casters. (Or even mobs that attack really slow.)